EMB-190 Captain reported autopilot failure including autothrottles followed by the First Officer side navigation display failure. The flight returned to the departure airport and made an overweight landing.

Narrative

On Date; relative to Aircraft X ZZZ-ZZZZ; the following occurred. Crew reported at aircraft about 15 minutes early; following just over a minimum rest period at the hotel. Flight blocked out 7 minutes early; having an engine bleed maintenance deferral. Normal taxi; First Officer takeoff; and departure; considering the above deferral. Climbing through about transition altitude; during an ATC communication; the autopilot; and auto throttles dis-connected with their resultant audible and visual alerts. Very shortly thereafter numerous EICAS messages also sounded and appeared; the first/top two being amber; 'AT FAILURE'; and 'SHAKER ANTICIPATED'. With FO (First Officer) hand flying the aircraft and working the radios; Captain performed the above QRH procedures; the second of which limited our speed to .50 mach; along with other flight and performance limitations. Request made to ATC to stop our climb at 22;000 feet.Advised cabin crew that we may be returning to ZZZ; not to start any customer services; and to ask deadheading E190 Captain if he could come up to the cockpit. When he arrived we requested that he stay up there and work the ATC radios to relieve some of our workload; and just to have an extra set of eyes; ears; and expertise. Attempted to contact AIRINC for a phone patch to Operations Control with no success; ACARS message sent to Operations Control got no reply; and radio calls made to ZZZ with no responses until close in. Due to the operational limitations required by the QRH procedures; we elected to return to ZZZ which involved an overweight (OW) landing and its QRH procedures. While FO was hand flying the return; some minutes after the original messages; the 'IRS2 FAILURE' EICAS message appeared and the FO flight displays failed.We swapped duties; with Captain now hand flying the aircraft back to ZZZ and resultant overweight landing; and with the FO doing the overweight landing QRH procedures and other PM (Pilot Monitoring) and approach prep tasks; with backup by additional crew member Captain on jumpseat. Swapped IRS2 and First Officer displays returned. Hand flew return; ILS XXL approach to a smooth; OW landing at 99;300 lbs. Same crew completed legs 3 and 4 early that duty day. Kudos must be given to the entire flight crew; cabin crew; our 'drafted' additional flight deck ACM; and station crews who got us back on schedule safely; quickly and efficiently.